Tumors, such as brain tumors, may be treated by heat (also referred to as hyperthermia or thermal therapy). In particular, it is known that above 57° C. all living tissue is almost immediately and irreparably damaged and killed through a process called coagulation necrosis or ablation. Malignant tumors, because of their high vascularization and altered DNA, are more susceptible to heat-induced damage than normal tissue. Various types of energy sources may be used, such as laser, microwave, radiofrequency, electric, and ultrasound sources. Depending upon the application and the technology, the heat source may be extracorporeal (i.e., outside the body), extrastitial (i.e., outside the tumor), or interstitial (i.e., inside the tumor). One example treatment of a tissue includes interstitial thermal therapy (ITT), which is a process designed to heat and destroy a tumor from within the tumor itself. In this type of therapy, energy may be applied directly to the tumor rather than passing through surrounding normal tissue, and energy deposition can be more likely to be extended throughout the entire tumor.
Further, tumors and other abnormal cellular masses may be treated using a cryosurgical or cryotherapy technique where extreme cold conditions are applied to damage or destroy tissue. In one example, a coolant, such as liquid nitrogen or liquid argon, may be circulated within a probe device (cryoprobe) while in contact with tumorous tissue to freeze tissue within the vicinity of the cryoprobe.